#include<iostream>
#include<math.h>
using namespace std;
int main() {
	int a, b, c = 0;
	double x, y = 0, z;
	int s[100];

	cin >> a;
	for (b = 0; b < a; b++) {
		cin >> s[b];
		c += s[b];
	}
	x = c * 1.0 / a;
	for (b = 0; b < a; b++) {
		y += (s[b] - x) * (s[b] - x);
	}
	z = sqrt(y / a);
	cout << z;
	return 0;
}
